Diffusion tensor imaging of forearm nerves in humans

Abstract

Purpose To implement diffusion tensor imaging (DTI) protocol for visualization of peripheral nerves in human forearm. Materials and Methods This HIPAA-compliant study was approved by our institutional review board and written informed consent was obtained from 10 healthy participants. T1-and T2-weighted turbo spin echo with fat saturation, short tau inversion recovery (STIR), and DTI sequences with 21 diffusion encoding directions were implemented to acquire images of the forearm nerves with an 8 channel knee coil on a 3T MRI scanner. Identification of the nerves was based on T1-weighted, T2-weighted, STIR and DTI-derived fractional anisotropy (FA) images. Maps of the DTI derived indices, FA, mean diffusivity (MD), longitudinal diffusivity (λ//) and radial diffusivity (λ⊥) along the length of the nerves were generated. Results DTI-derived maps delineated the forearm nerves more clearly than images acquired with other sequences. Only ulnar and median nerves were clearly visualized on the DTI-derived FA maps. No significant differences were observed between the left and right forearms in any of the DTI-derived measures. Significant variation in the DTI measures was observed along the length of the nerve. Significant differences in the DTI measures were also observed between the median and ulnar nerves. Conclusion DTI is superior in visualizing the median and ulnar nerves in the human forearm. The normative data could potentially help distinguish normal from diseased nerves.

High resolution diffusion tensor imaging of human nerves in forearm

“…The FA maps at higher spatial resolution, acquired with the optimized DTI scan parameters allowed visualization of the superficial radial, median, and ulnar nerves consistently on all the scans, whereas only ulnar and median nerves were clearly visualized at lower spatial resolution (). We believe that our studies are the first to systematically evaluate the effect of various acquisition parameters on the visualization and quantification of the diffusion anisotropy in peripheral nerves.…”

“…Recently, DTI has attracted considerable attention for the evaluation of peripheral nerves in patients with nerve diseases and injuries, and monitoring nerve degeneration and regeneration after traumatic nerve injuries (). Quantitative DTI measures such as FA, MD, λ // , and λ ⊥ on healthy controls were obtained for comparison with the diseased/injured nerves to assess nerve integrity, repair, and other diseases (). Preclinical studies suggested the utility of specific DTI indices in assessing peripheral nerve injury and repair ().…”

Peripheral Neuropathy: Detection with Diffusion-Tensor Imaging

“…Recent studies on peripheral nerve DTI have demonstrated its general feasibility (8)(9)(10)(11)(12) in the accurate visualization of nerves by means of their fractional anisotropy (FA). FA indicates the directional preference of free water proton diffusion, which physiologically has high values in intact peripheral nerves (reviewed in references 9 and 13).…”

Morphological Detection and Functional Assessment of Regenerated Nerve after Neural Prosthesis with a PGLA Nerve Conduit

“…Skorpil14 applied a new MRI technique, diffusion direction–dependent imaging (DDI), after processing to isolate human sciatic nerve images from surrounding tissue images, to clearly display nerve morphology. In 2012, Zhou et al 15. used the diffusion tensor imaging technique to examine median and ulnar nerves in the human forearm, which enabled to display a nerve in the human forearm with a diameter of about 3 mm.…”